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Renin Angiotensin Mechanism.

Organization of Skeletal Muscles.

 Organization of Skeletal Muscles.

Introduction:

  • A whole skeletal muscle is considered an organ of the muscular system. 

  • Each organ or the muscle consists of skeletal muscle tissue, connective tissue, nerve tissue, and vascular tissue.

  • Skeletal muscles vary considerably in size, shape, and arrangement of fibers. 

  • They range from extremely tiny strands such as the stapedius muscle of the middle ear to large masses such as the muscles of the thigh. 

  • Some skeletal muscles are broad in shape and some narrow. 

  • In some muscles the fibers are parallel to the long axis of the muscle; in some they converge to a narrow attachment; and in some they are oblique.

Structure of Skeletal Muscle:

  • Each skeletal muscle fiber is a single cylindrical muscle cell. 

  • An individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers bundled together and wrapped in a connective tissue covering. 

  • Each muscle is surrounded by a connective tissue sheath called the epimysium.

  • Fascia, connective tissue outside the epimysium, surrounds and separates the muscles. 

  • Portions of the epimysium project inward to divide the muscle into compartments. 

  • Each compartment contains a bundle of muscle fibers. 

  • Each bundle of muscle fiber is called a fasciculus and is surrounded by a layer of connective tissue called the perimysium. 

  • Within the fasciculus, each individual muscle cell, called a muscle fiber, is surrounded by connective tissue called the endomysium.

  • The connective tissue covering furnishes support and protection for the delicate cells and allows them to withstand the forces of contraction. 

  • The coverings also provide pathways for the passage of blood vessels and nerves.

  • The epimysium, perimysium, and endomysium extend beyond the fleshy part of the muscle, to form a thick ropelike tendon. 

  • The tendon forms indirect attachments from muscles to the periosteum of bones or to the connective tissue of other muscles. 

  • Skeletal muscles have an abundant supply of blood vessels and nerves. 

  • Before a skeletal muscle fiber can contract, it has to receive an impulse from a nerve cell. 

  • Generally, an artery and at least one vein accompany each nerve that penetrates the epimysium of a skeletal muscle. 

Commonly Asked Question:

  1. Write a short note on the structure of a skeletal muscle.
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